I stumbled across this rather fascinating review article entitled, "The Underappreciated Role of Muscle in Health and Disease
". A lot of it is stuff that I was vaguely aware of, but one thing that I really didn't appreciate is the extent to which the body's protein needs can rise substantially with acute illness or injury. Given that your body will take the protein from your muscles if it can't get it from your diet, that might explain part of why an acute injury or illness can cause so much long term debility.
The article also makes a good case that the current dietary recommendations for protein were developed without taking into account requirements for preserving or increasing muscle mass, and should probably be revised upwards. I agree, although it's worth noting that the average American eats nearly twice the currently recommended amount of protein per day, so changing the guidelines wouldn't necessarily have a dramatic effect on overall health.
Anyway, I had a fairly strenuous workout yesterday, and quite a bit of my muscle mass is complaining today, so it's nice to be reminded that it's doing me some good.